Self destruction switch



March 14, 1961 w. B. MCLEAN SELF DESTRUCTION SWITCH Filed Feb. 3. 1947 HCF- IIIIIII nmnnnummm glu/um WILLIAM E. NIE-LEAN 1 2,974,598 SELF DESTRUCTION SWITCH William B. McLean, Washington, D.C., assignor to the United States of America as represented by the Secretary of War Filed Feb. 3, 1947, Ser. No. 726,195 4 Claims. (Cl. 102-70.2)

(Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes,"'without the payment to me Vof any royalty thereon.

This invention relates to delay switches for insuring the destruction of an ordnance projectile at the end of a predetermined time if the usual fuze mechanism has not exploded the projectile by the end of the latter interval.

A primary object of the invention is the provision of a rotary gear switch for closing the electric circuit to the detonator at the end of a considerable delay period.

Rockets or other projectiles of the type used against enemy aircraft are usually provided with a fuze intended to detonate them at or near the target. Such fuze might be a contact fuze, a preset time fuze, a fuze set by air travel or any other known type of fuze, as my invention is equally applicable to any of these fuzes. All of these uzes have the characteristic of being in a dangerous condition if the rocket misses its target. When used in friendly territory, it is highly undesirable that such projectiles should be allowed to fall to the ground after a miss. My invention provides means for causing the projectile to destroy itself after a miss but before it falls to ground, and is applicable to any fuze employing an electrically actuated detonating squib.

Fig. l is a schematic view, in longitudinal section, of the nose of a projectile embodying my invention.

Fig. 2 is an enlarged detailed elevation view taken on line Z-Z of Fig. 3 thru the self-destruction switch and powder train interrupter contained in housing 3.

Fig. 3 -is a sectional plan View taken on line 3 3 of Fig. 2.

Projectile 20 carries vanes 21 which rotate arming shaft 22 when the projectile travels through the air toward its target. Shaft 22, through gear system 23, rotates shaft 1 at a comparatively slow speed. Shaft 1 is adapted to rotate in bearing 2 formed integrally with the cup-shaped portion 3 which is xed to the projectile; shaft 1 has fixed thereon the gear 4 meshing with an idler gear 5 which is adapted to roll around gear 4. Idler gear 5 meshes with teeth 6 cut in the inner periphery of the cup-shaped portion 3. Loosely fitting the cup-shaped portion 3 is an axially bored rotor 7 of insulating material. Rotor 7 is locked to shaft 1 by the springpressed pin 8 which extends into a recess 9 in the shaft 1.

-It will be observed that initial rotation of shaft 1 rotates gear 4, idler gear 5 and also the rotor 7. After the rotor 7 has rotated 90, however, the outer end of pin 9 is moved into the slot 10 in the inner wall of the cup 3 by its surrounding spring, and subsequent rotation of shaft 1 rotates gears 4 and 5 but not rotor 7, which is now freed from shaft 1.

A squib 11 inserted into the rotor 7 is rotated 90 with the rotation of the piston into the dotted line position shown in Fig. 3. It will be observed that in this latter position the squib 11 is directly beneath the arcuate contacts 12 and 13 mounted on the upper Wall of the cup 3. These are spring contacts extending down into the space 14, and are connected, through insulating bushings 15 and 16, respectively, to a suitable source of electrical potential schematically indicated at 19. Squib 11 is provided With contacts 17 and 18, so dmensioned that when 2,974,598 Patented Mar. 14, 1961 rotor 7 is in its final position, locked to cup 3, contacts 12 and 13 engage contacts 17 and 18, respectively, to connect the squib 11 to its normal detonating circuit, which consists of a suitable source of potential. This is schematically shown as a battery 19, and a switch 25, which may be anysuitable circuit closing device operated in any known manner to detonate said squib to destroy the target. One side of the potential source 19 -is grounded to the frame as shown at 26. Idler gear 5 is also grounded to the frame through its direct metallic connection to shaft 1, as is schematically indicated at 27.

It will thus be seen that, some time after the'rotor is locked to cup 3, gear 5 will rotate into its extreme position where it electrically engages ungrounded contacts 12 and 17. This completes the circuit through contact 17 to ground (at 27), from ground 26, through source 19, contacts 13 and 18, through squib 11 and back to contact 17, thus detonating the squib, and hence, through booster 24, explodes the main charge (not shown) to destroy the projectile.

The normal tiring circuit of the projectile is completed during the counter-clockwise revolution of the idler gear 5 from the locked position of the rotor 7 at 10 (Fig. 2). If for any reason normal firing does not occur during this period the self-destruction switch just described operates to destroy the projectile.

The switch 25 is contained in the explosion determining section 28 of the fuze, which may be a timing device or inertia device, or any other known type of explosion determining device. The particular control device used in section 28 is no part of my invention which is applicable to a number of control devices well known in the art.

I claim:

1. Firing means for fuzed explosive projectiles comprising a drive shaft, a detonator holder, a detonator normally held in said holder in an unarmed position, electrical circuit means for firing said detonator, means actuated by said drive shaft for moving said detonator holder .to an armed position, a xed annular gear, an idler gear meshing with said annular gear, a gear mounted on said shaft and meshing with said idler gear to rotate said idler gear within said annular gear into position to actuate said electrical circuit means to lire said detonator after a predetermined number of revolutions of said drive shaft.

2. Self-destructive means for a fuzed anti-aircraft explosive projectile having delayed arming means actuated Iby a rotating shaft, comprising a rotatable member latched to said shaft, electrical contact means carried by said member, means for releasing said rotating member from said shaft after said shaft has rotated a predetermined amount, a rst gear mounted for concentric rotation With said shaft, a xed annular gear member concentrically mounted with respect to said shaft, a planetary gear engaging both of said gears and mounted for rotation by said first gear, said planetary gear being positioned to actuate said electrical contact means after a predetermined number of revolutions of said shaft, and detonating means fired by the closing of said contact means.

3. Self-destruction means for a fuzed anti-aircraft explosive projectile comprising a `rotatable shaft, means for rotating said shaft after the projectile is in free flight, delayed normal arming means actuated by said shaft for arming the projectile after it is in free ilight, normal detonating means for detonating said projectile to destroy a target during said free flight, an electric circuit for detonating said projectile, ungrounded contact means for said circuit, a gear mounted on said shaft for rotation therewith, a fixed annular gear, a planetary gear engaging both of said first and second named gears for planetary rotation about said shaft and positioned to engage said contact means to ground Asaid circuit to detonate said -squib after a predetermined number of revolutions of said drive shaft, substantially later than the normal detonating period whereby the projectile will be 4destroyed if norrral detonation does not occur;rv i

4, The invention as recited in claim 3, lwherein the normal arming means carried by the rotatable shaft comprises a rotatable detonator holder latchedto said shaft for rotation therewith to `a normal arming position', and means for releasing said detonator holder from said shaft and locking it in armed Iposition after a predeterr Y v 4 mined number of revolutions of said shaft, less than the number of revolutions required to move the planetary gear into its iinal position.

`References Cited in the 'file of this patent UNI-TED STATES PATENTS Great Britain Ian. 13, 1912 

